OS : Windows 10 Pro 64-bit (10.0, Build 14393) (14393.rs1_release.160715-1616)
Spotify Version : 18.104.22.168.g15edf1ec
Both including previous builds and versions.
Been having this issue ever since I first subscribed to Spotify Premium, more than 3 months at the very least.
I downloaded songs to be available offline (green downloaded icons and stuff) -- goes to offline mode -- plays song is that available in offline mode -- some tracks appears to be corrupted as the playback got stuck halfway.
Self-troubleshooting including :
1. clean reinstallation
2. moving cache savepath from external HDD to internal HDD.
3. clearing off list of offline devices in Spotify account pages.